April 1, 1981 DOS/VS Supervisor Macros and Logical Transients Support for VSAM CMS supports VSAM is based VSAM for OS on DOS/VS. and DOS users. However, the eMS support of
The DOS/VS supervisor macros shown in Figure DOS/VS VSAM routines, are supported by eMS. 41, which are used by the r- I 1 Macro 1 ICDLOAD I 1 1 I I 1 IFREE I 1 FREEVIS 1 I GETVIS HOLD POST RELEASE SECTVAL USE L- ISVC I INumberl Extent of eMS Support 65 DOS/VS macro for internal use only. Loads a VSA! core image phase. CMS searches the VSAM saved
segment for the phase instead of the DOS/VS SVA area. If an anchor table entry does not exist, CMS fetches the phase, creates an anchor table entry,
and sets register values as DOS/VS would set them.
36 No operation is performed by CMS. 62 CMS invokes its free storage handler to return
35 40 64
the storage that is no longer needed. CMS follows
the DOS/VS register and return code conventions. CMS invokes its free storage handling routines
to obtain free storage; it follows the DOS/VS register and return code conventions. The SVA operand does not apply to CMS and is not supported.
The PAGE and POOL operands are ignored by CMS. No operation is performed by CMS. When a POST macro is issued for an ECB, Byte 2 Bit 0 is set on. The SAVE=savarea operand is ignored by CMS. CMS reduces the RURTBL counter for the resource
by one. CMS uses the data in registers 0 and 1 to calculate
the sector number and returns the sector number in
register O. If any errors occur
CMS returns I'FF'
in reqister o. DOS/VS macro for internal use only. CMS supports
this macro only to the extent necessary to support VSAM. If a counter for a particular resource is
zero, CMS increments the counter by one and returns
a zero in register o. If a counter is greater than
zero, CMS increments the counter by one and returns
an eight in register o.
Fiqure 41. DOS/VS VSAM Macros Supported by CMS CMS distributes the DOS/VS transients that are needed in the VSAM support. Thus, OS users do not need to have the DOS/VS system pack
online when they are and executing VSAM programs. CMS uses all of the DOS/VS VSAM except those that build
and release JIBs (job information blocks). The JIB is not supported in CMS and, thus, neither are the B-transients ($$BJIBOO, $$BJIBFF, and $$BOVS03) that control the JIB. Part 3. Conversational Monitor System (eMS) 311
April 1, 1981
The CMS/DOS shared segment contains the B-transients that are
simulated for DOS support in CMS. Three B-transients that pertain only
to VSAM are included in the VSAM saved segment: $$BOMSG1, $$BOKSG2, and
$$BENDQB. The $$BENDQB transient is called by the ENQB macro and
released by the DEQB macro. Storage Requirements
The VSAM and Access Method Services support in CMS requires both DASD
space and virtual storage.
The VSAM and Access Method Services support adds approximately 2K to
the size of the CMS nucleus. In addition, this support uses free
storaqe to execute the DOS/VS logical transients and for buffers and
work areas. VSAM issues a GETVIS macro to request free If the CMS/DOS environment is invoked with the VSAM option
SET DOS ON (VSAM part of the CMS/DOS virtual storage is set aside for VSAM use.
Disk storage requirements vary depending upon device type:
Number of cylinders Required
Device Usg OS User 2314- 10 --20- 2319 10 20 3330 Model 1 6 12 3330 Model 11 6 12 3340 15 30 3344 15 30 3350 3 6
Data Set Compatibility Considerations CMS can read and update VSAM data sets that were created under DOS/VS or OS/VS. In addition, VSAM data sets created under CMS can be read and
updated by DOS/VS or OS/VS. However, if you perform allocation on a minidisk in you cannot
use that minidisk in an OS virtual machine in any manner that causes
further allocation. DOS/VS VSAM (and, thus, CMS) ignores the format-5,
free space, DSCB, on VSAM disks when it allocates extents. If
allocation later occurs in an OS machine, OS attempts to create a
format-5 DSCB. However, the format-5 DSCB created by OS does not
correctly reflect the free space on the minidisk. In eMS, allocation
occurs whenever data spaces or unique data sets are defined. Space is
released whenever data spaces, catalogs, and unique data spaces are
deleted. ISAM Interface Program (liP) CMS does not support the VSAM ISAM Interface Proqram (lIP). Thus, any
program that creates and accesses ISAM (indexed sequential access
method) data sets cannot be used to access VSAM key sequential data
sets. There is one exception to this restriction. If you have (1) OS PL/I programs that have files declared as ENV(INDEXED) and (2) if the library routines detect that the data set being accessed is a VSAM data
set, your programs will execute VSAM I/O requests.
312 IBM VM/370 System Proqrammer's Guide
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